<?php
// +----------------------------------------------------------------------
// | ThinkCache
// +----------------------------------------------------------------------
// | Copyright (c) 2006-2012 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <liu21st@gmail.com>
// +----------------------------------------------------------------------
namespace Think\Cache\Driver;
/**
 * 文件类型缓存类
 * @author    liu21st <liu21st@gmail.com>
 */
class File {

    protected $options  =   array(
        'expire'        =>  0,
        'cache_subdir'  =>  false,
        'path_level'    =>  1,
        'prefix'        =>  '',
        'length'        =>  0,
        'temp'          =>  '',
        'data_compress' =>  false,
    );

    /**
     * 架构函数
     * @access public
     */
    public function __construct($options=array()) {
        if(!empty($options)) {
            $this->options =  array_merge($this->options,$options);
        }
        if(substr($this->options['temp'], -1) != '/')    $this->options['temp'] .= '/';
        $this->init();
    }

    /**
     * 初始化检查
     * @access private
     * @return boolen
     */
    private function init() {
        // 创建项目缓存目录
        if (!is_dir($this->options['temp'])) {
            if (!  mkdir($this->options['temp'],0755))
                return false;
        }
    }

    /**
     * 取得变量的存储文件名
     * @access private
     * @param string $name 缓存变量名
     * @return string
     */
    private function filename($name) {
        $name	=	md5($name);
        if($this->options['cache_subdir']) {
            // 使用子目录
            $dir    =   '';
            $len    =   $this->options['path_level'];
            for($i=0;$i<$len;$i++) {
                $dir	.=	$name{$i}.'/';
            }
            if(!is_dir($this->options['temp'].$dir)) {
                mkdir($this->options['temp'].$dir,0755,true);
            }
            $filename	=	$dir.$this->options['prefix'].$name.'.php';
        }else{
            $filename	=	$this->options['prefix'].$name.'.php';
        }
        return $this->options['temp'].$filename;
    }

    /**
     * 读取缓存
     * @access public
     * @param string $name 缓存变量名
     * @return mixed
     */
    public function get($name) {
        $filename   =   $this->filename($name);
        if (!is_file($filename)) {
           return false;
        }
        $content    =   file_get_contents($filename);
        if( false !== $content) {
            $expire  =  (int)substr($content,8, 12);
            if($expire != 0 && time() > filemtime($filename) + $expire) {
                //缓存过期删除缓存文件
                unlink($filename);
                return false;
            }
            $content   =  substr($content,20, -3);
            if($this->options['data_compress'] && function_exists('gzcompress')) {
                //启用数据压缩
                $content   =   gzuncompress($content);
            }
            $content    =   unserialize($content);
            return $content;
        }
        else {
            return false;
        }
    }

    /**
     * 写入缓存
     * @access public
     * @param string $name 缓存变量名
     * @param mixed $value  存储数据
     * @param int $expire  有效时间 0为永久
     * @return boolen
     */
    public function set($name,$value,$expire=null) {
        if(is_null($expire)) {
            $expire =  $this->options['expire'];
        }
        $filename   =   $this->filename($name);
        $data   =   serialize($value);
        if($this->options['data_compress'] && function_exists('gzcompress')) {
            //数据压缩
            $data   =   gzcompress($data,3);
        }
        $data    = "<?php\n//".sprintf('%012d',$expire).$data."\n?>";
        $result  =   file_put_contents($filename,$data);
        if($result) {
            if($this->options['length']>0) {
                // 记录缓存队列
                $queue_file =   dirname($filename).'/__info__.php';
                $queue  =   unserialize(file_get_contents($queue_file));
                if(!$queue) {
                    $queue  =   array();
                }
                if(false===array_search($name, $queue))  array_push($queue,$name);
                if(count($queue) > $this->options['length']) {
                    // 出列
                    $key =  array_shift($queue);
                    // 删除缓存
                    unlink($this->filename($key));
                }
                file_put_contents($queue_file, serialize($queue));
            }
            clearstatcache();
            return true;
        }else {
            return false;
        }
    }

    /**
     * 删除缓存
     * @access public
     * @param string $name 缓存变量名
     * @return boolen
     */
    public function rm($name) {
        return unlink($this->filename($name));
    }

    /**
     * 清除缓存
     * @access public
     * @param string $name 缓存变量名
     * @return boolen
     */
    public function clear() {
        $path   =  $this->options['temp'];
        if ( $dir = opendir( $path ) ) {
            while ( $file = readdir( $dir ) ) {
                $check = is_dir( $file );
                if ( !$check )
                    unlink( $path . $file );
            }
            closedir( $dir );
            return true;
        }
    }
}